Solid Propellant Fundamentals...2014/10/10 · Propellant Grain Stress and Strain and Reaction...
Transcript of Solid Propellant Fundamentals...2014/10/10 · Propellant Grain Stress and Strain and Reaction...
Solid Propellant
Fundamentals
Solid Design Team
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ContentBasic Relations
-Jack
Burning Rate Relations and Enhancements
-Scott
Other Performance Issues
-Jason
Propellant Grain and Grain Configuration
-Nicholas
Propellant Grain Stress and Strain and Reaction Control Systems
-Tarique and Esteban
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Basic Solid Rocket Motor
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(1)
Burning Rate Relation with Temperature
● Conditioning
● Acceptable
temperature limits○ 219 K (-65℉)
○ 344 K (160℉)
● Variations○ Pressure
○ Operating time
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Temperature Coefficients
● Temperature
sensitivity of
burning rate
● Temperature
sensitivity of
pressure
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Burning Enhancement by Erosion
● Occurs in port passages
● More likely when port
area is small relative to
throat area
● Turbulent mixing
increases heat transfer
● Propellant consumed
more rapidly
● Early burnout of the web6
Erosive Burn Equation
● 1956 by Lenoir and Robillard
● Based on adding 2 burn rates
o r0: function of pressure
and Tb
o re: increase due to erosion
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Other Burning Rate Enhancements
● Spinning
● Embedding of wires
● Wire staples
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Performance Issues
Overall Performance Parameters
Solid only Performance Parameters
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Overall Performance Parameters
● Thrust (Ch. 2 & 3)
● Effective exhaust velocity (Ch.2)
● Specific impulse (Ch. 2 & 3)
● Propellant mass fraction (Ch. 2)
● Flame Temperature (Ch. 5)
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Total Impulse
11Figure 12-13
Solid Performance Parameters
● Ideal nozzle exhaust velocity
● loaded weight
● Total-impulse-to-loaded-weight-ratio
● Volume impulse
● Thrust-to-weight-ratio
● Temperature limits
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Propellant Grain and Grain Configuration
Grain: shaped mass of processed solid propellant inside the rocket motor
(2)
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Grain Configuration Performance
Propellant Grain and Grain Configuration
(2)
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Single Grain Configuration
Propellant Grain and Grain Configuration
(2)
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Propellant Grain and Grain Configuration
(2)
Three Dimensional Grain Configuration
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Grain Configuration Dual Thrust
Propellant Grain and Grain Configuration
(2)
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Grain Configuration Dual Thrust and End Burning Grain Coning Effect
Propellant Grain and Grain Configuration
(2)
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Solid Propellant Handling and Storage
WHY?
● Avoid inconsistent burn rates as a result of grain damage
WHEN?
● During manufacture of propellant
● Transport
● Storage
● Operation
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Factors that Induce Grain Deformations
● Thermal cycling and/or external heat through the case
● Cooling Rate after manufacturing causing compressive stress and strain
● Vibrations during transport/handling
● Undergoing high acceleration: including flight maneuvers
● Gravity slump: storage (Mostly for large motors)
● Imperfections during manufacture20
Propellant Grain Stress and Strain
● Undamaged propellant
○ High max stress and strain
● Damaged propellant
○ Reduced max stress and strain
● Results in grain fractures and cracks, grain
debonding from case line and insulation.
(2)
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Grain Damage Plot
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Handling
● Manufacturer to WSU
● Inspection and handling on campus
● Over 800 miles
● About 13 hours trip to Green River, UT
● Pre launch
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Grain damage
● Most propellants are viscoelastic i.e non-linear
viscoelastic behavior
● Adhesive between individual solid particles and
binder gets broken down
○ Caused by cyclic load/thermal stress
○ Maximum stress/strain diminishes with
each cycle
● Varies between space motor to tactical missile
to ballistic missile
(3)
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Reaction Control Systems
● 2 types of RCS
o Main exhaust RCS
o Monopropellant RCS
● Main exhaust RCS used during
mid-flight maneuvers
● Monopropellant RCS used for
orbital maneuvers for finer
maneuvering25
Orion Launch Abort System (LAS)
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Summary● Knowing how burning rate relates and changes with mass flow, pressure,
and temperature is key to solid motor design.
● Grain configuration is necessary in large scale motors, but can be
neglected in our design case.
● For our case, handling is a big deal since we’ll be driving it down to
competition.
● RCS won’t be used in the competition rocket since our rocket will have
roughly a 2 second burn time.
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Bibliography(1)www.dtic.mil/cgi-bin/GetTRDoc?AD=ada425146
(2)Rocket Propulsion Elements by George P. Sutton and
Oscar Biblarz, 8th ed.
http://www.csar.illinois.edu/rocstar/
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